Distribution of organisms

Distribution of organisms

1. Organisms live in different places because the environment changes.

   • A habitat is the place where an animal lives.
   • The distribution of an organism is where that organism is found e.g in part of a playing field.
   • Where an organism is found is affected by environmental factors.
     • Such as: Temperature, Amount of light, availability of water, oxygen, carbon dioxide and nutrients.
   • An organism might be more common in one area than another due to differences in environmental factor between the 2 areas.
     • For example, in a field you might find that daisies are more common in the open than under trees, as there is more light available in the open.
   • There are a couple of ways to study the distribution of organisms.
     • You can: Measure how common an organism is in 2 sample areas and compare them or Study how the distribution changes across and area.

2. Quadrants are used to study the distribution of small organisms.

   • A quadrant is a square frame enclosing a known area e.g 1m square. Used to compare how how common an organism is in 2 sample areas by:
     • 1) Place a 1m square quadrant on the ground at random point within the first sample area.
       • E.g divide the quadrant up into a grid and use a number generator to pick a square.
     • 2) Count all the organisms within that quadrant.
     • 3) Repeat steps 1 and 2 as many times as you can.
     • 4) work out the mean number of organisms per quadrant within the first sample area.
     • 5) Repeat steps 1 - 4 in another sample area.
     • 6) Finally compare the 2 means. E.g you might find 2 daisies per m square in tthe shade and 22 in the open (a lot more).